Grep is broken - use perl instead

In the course of running various grep(1) combination to find various defects in source files I ran into inherent grep(1) difficulties. It seems that the regular expression syntax in grep(1) is very limited and so it's better to use perl to solve these issues as it's regular expression support is fantastic. A small script can solve all your grepping needs. So here it is. Please comment with fixes and I'll incorporate them if you want to add features.

(Note: this post was imported from an old WordPress blog, and the import ate the < characters in the script — taking the loop condition, the open and the while line with them. The listing below is reconstructed. Note the while line uses my $line rather than the my($line) style used elsewhere here: the parenthesised form puts the readline in list context, which reads only the first line of each file.)

#!/usr/bin/perl -w

# This is a general script to grep using perl to overcome some of the deficiencies
# of grep(1) grepping...

use strict;
use diagnostics;

my($pattern)=$ARGV[0];
my($debug)=0;
my($print_filename)=1;

for(my($i)=1;$i<@ARGV;$i++) {
        my($filename)=$ARGV[$i];
        if($debug) {
                print "doing file [$filename]\n";
        }
        open(FILE,"<",$filename) || die("unable to open file [$filename]: $!");
        while(my $line=<FILE>) {
                if($line=~$pattern) {
                        if($print_filename) {
                                print $filename.": ";
                        }
                        print $line;
                }
        }
        close(FILE) || die("unable to close file [$filename]: $!");
}